OCR Text |
Show or THE EXTRACTION or THE CATARACT. 456 this simple accident, brings out the point of the knife too soon, and instead of making a semi-circular incision of, the cornea near its margin, makes a cut, terminating nearly in the middle of the cornea, thus : ,‘fi'r<~.;.-‘..‘_->‘.V‘A‘ a}. - 9m": st? OF THE EXTRACTION OF THE CATARACT. 7'. If by any accident the aqueous humour should escape, and the margin of the iris should fall before the edge of the knife, in this manner, we cannot then carry forward the knife. ‘i This accident requires calmness. Vie know how it has happened, and this knowledge teaches us to remedy it. A little of the aqueous humour has escaped, and the iris is A. The proper course of the incision, marked by a dotted line. B. The course which the knife has taken in cases, where " {new mun I have seen. the operator embarrassed, by the eye turning {nu n'urd. must be withdrawn a little, and brought before the edge of the iris, and made to pierce the cornea lower down, than would be necessary to make an incision of due extent. By this change of the direction of the knife, we have made a section of the cornea, without injury to the iris, but it is not of sufficient size to let the cataract pass, we must therefore have recourse to the scissors to enlarge it. 9. When we have made the section of the cornea too small, and the lens or cataract does not come spontaneous- practice not to be imitated, as the advantage of it, bears no .. * Baron \Venzel and Mr. Ware, give the direction to rub the cornea, as | [~W't" 'II‘ O‘tgramm' 3-9," ,. 7"C-. "3",. .5"? -... . . "av-rs. 3.... -..,. 5. It is to prevent this motion of the pupil towards the nose, that practitioners have exerted all their ingenuity, to form a speculum to fix the eye. The first objection to the use of the speculum, is, that it engages the hand of the surgeon, when he should have his finger free, to press upon the surface of the cornea ; and secondly, that the speculum operating by pressure on the eye, is apt to force the aqueous hu~ mour out, before the incision is completed. 6. Some oculists have recommended, that the capsule of the lens, should be punctured, before the incision of the cornea be completed, viz. as the knife is carried through the anterior chamber of the aqueous humour, they depress the point into the pupil, to pierce the capsule. But this is a pressed forwards : we must restore the equilibrium then, by pressing gently on the cornea. This throws back the margin of the iris behind the edge of the knife, and again we can carry the knife straight forwardae. 8. But if the aqueous humour, has escaped in such a quantity, that the iris has come in contact with the cornea, and lies before the edge of the knife, we cannot finish the section of the cornea with the knife. The point of the knife proportion to the danger. The consequence of this manoew vre, too often will be, that the aqueous humour will escape ; then the iris will press forward on the edge of the knife, and the incision cannot be completed with the knife. if there was a sympathy betwixt the cornea and iris : but as I have not been able to ascertain that any cormexion subsists betwixt the rubbing of the one, and the contraction of the other, I have given this intelligible reason for pressing the cornea. |